Liters vs Gallons: Understanding US vs UK Differences
Published on September 17, 2025 by UnitConvertersOnline Team
Have you ever rented a car abroad or read a recipe only to be puzzled by the mention of gallons instead of liters? To make matters even more confusing, there isn’t just one gallon—there are two! The US gallon and the UK (imperial) gallon are different, and knowing how they relate to liters can save you from major misunderstandings. In this guide, we’ll explain the differences, give you the formulas, show conversion tables, and offer practical examples.
What Is a Gallon?
A gallon is a unit of volume traditionally used to measure liquids like water, milk, or fuel. While most of the world has switched to the metric system (liters, milliliters), the gallon remains in use in some countries, particularly for fuel and beverages. However, the problem is that the size of a gallon is not the same everywhere.
The Two Types of Gallons
There are two main gallon measurements you’ll encounter:
- US gallon: Common in the United States. 1 US gallon = 3.785 liters.
- UK (imperial) gallon: Used in the United Kingdom and some Commonwealth countries. 1 UK gallon = 4.546 liters.
This difference of about 0.76 liters per gallon is significant when buying fuel, cooking, or comparing product sizes across regions.
Conversion Formulas
- Liters = US gallons × 3.785
- Liters = UK gallons × 4.546
- US gallons = Liters ÷ 3.785
- UK gallons = Liters ÷ 4.546
Want to skip the math? Use our liters to gallons converter for instant results.
Conversion Tables
Here are quick reference tables for both US and UK gallons to liters:
US Gallons to Liters
| US Gallons | Liters |
|---|---|
| 1 | 3.785 |
| 5 | 18.925 |
| 10 | 37.85 |
| 20 | 75.7 |
UK Gallons to Liters
| UK Gallons | Liters |
|---|---|
| 1 | 4.546 |
| 5 | 22.73 |
| 10 | 45.46 |
| 20 | 90.92 |
Example Calculation
Imagine you’re in the US and buy 10 gallons of gasoline. How many liters is that?
10 × 3.785 = 37.85 liters
Now, if you bought 10 UK gallons instead, it would be:
10 × 4.546 = 45.46 liters
That’s a difference of over 7.5 liters!
Real-World Applications
Understanding liters and gallons is essential in many areas of life:
- Fuel economy: Car efficiency is measured in miles per gallon (mpg) in the US, but in liters per 100 kilometers in most other countries.
- Cooking: Recipes from the UK and US may list gallons, but the amounts differ depending on which gallon is meant.
- Trade: Importing beverages, chemicals, or bulk liquids requires accurate conversions to avoid shortages or overages.
Why the Difference Exists
The UK gallon was originally based on 10 pounds of water, while the US gallon was defined differently. Over time, these differences became permanent. Today, both remain in use but in different parts of the world, which can cause confusion for travelers and businesses.
Conclusion
The gallon is not a single standard unit—it comes in two major forms: the smaller US gallon (3.785 L) and the larger UK gallon (4.546 L). Understanding these differences and being able to convert to liters is crucial for accuracy in daily life, international trade, and travel. When in doubt, rely on tools like our liters to gallons converter to avoid mistakes and ensure precision.